Field of the Invention
The invention relates to a multi-level furnace and to a method for the thermal treatment of a material flow, preferably a material flow containing carbon.
Description of Related Art
The thermal treatment of a material flow is understood as also meaning in particular a torrefaction, in which biomass is thermally treated by pyrolytic decomposition at relatively low temperatures of 250° to 450° C. with the exclusion of air.
WO 2012/007574 A1 discloses a device and a method for the drying and torrefaction of at least one carbon-containing material flow in a multi-level furnace. The drying and the torrefaction take place there in two different process chambers that are spatially separate from one another. This spatial separation makes it possible for the atmosphere to be specifically set to suit the respective process (drying or torrefaction). In this way, the efficiency, and consequently also the throughput, of the device can be increased significantly. The transfer device provided between the two process chambers is not specified any more precisely in this document. It is however conceivable to realize the gas separation of the process chambers by cellular wheel sluices or double swing valves. However, the installation of these sluices is only possible outside the process chambers, and so a separate furnace is required for each process chamber.